<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <p class='demo'>hello JavaScript</p>
</body>
<script>
    // 获取<p class='demo'>hello JavaScript</p>内部文案

    const pList = document.getElementsByClassName("demo");
    const p =  pList[0];
    console.log(p.innerHTML);
    console.log(p.innerText);

</script>
</html>